The face of Mars

The Hubble Space Telescope focuses on the full disk of Mars, with a head-on view of a dark feature known as Syrtis Major. Hubble astronomers could make out features as small as 12 miles wide.
(AURA / STSCI / NASA)
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Red, white and blue planet

Two decades before Pathfinder, the Viking 1 lander sent back America's first pictures from the Martian surface. This 1976 picture shows off the lander's U.S. flag and a Bicentennial logo as well as the planet's landscape.
(NASA)
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Grand canyon

This is a composite of Viking orbiter images that shows the Valles Marineris canyon system. The entire system measures more than 1,875 miles long and has an average depth of 5 miles.
(NASA)
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Red rover

A mosaic of eight pictures shows the Pathfinder probe's Sojourner rover just after it rolled off its ramp. At lower right you can see one of the airbags that cushioned Pathfinder's landing on July 4, 1997.
(NASA)
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Twin Peaks at their peak

The Pathfinder probe focuses on Twin Peaks, two hills of modest height on the Martian horizon. Each peak rises about 100 feet above the surrounding rock-littered terrain.
(NASA)
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Blue horizon

A Martian sunset reverses the colors you'd expect on Earth: Most of the sky is colored by reddish dust hanging in the atmosphere, but the scattering of light creates a blue halo around the sun itself.
(NASA / JPL)
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Two-faced Mars

The image at left, captured by a Viking orbiter in the 1970s, sparked speculation that Martians had constructed a facelike monument peering into space. But the sharper image at right, sent back in 1998 by Mars Global Surveyor, spoiled the effect.
(NASA)
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A monster of a mountain

Mars' highest mountain, an inactive volcano dubbed Olympus Mons, rises as high as three Everests and covers roughly the same area as the state of Arizona. Mars Global Surveyor took this wide-angle view.
(MSSS / NASA)
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From Mars with love

This valentine from Mars, as seen by Mars Global Surveyor, is actually a pit formed by a collapse within a straight-walled trough known in geological terms as a graben. The pit spans 1.4 miles at its widest point.
(MSSS / NASA)
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Sandy swirls

An image taken by Mars Global Surveyor shows a section of the northern sand dunes on Mars' surface. The dunes, composed of dark sand grains, encircle the north polar cap.
(JPL / NASA)
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Curls of clouds

Global Surveyor focuses on a storm system over Mars' north polar region. The north polar ice cap is the white feature at the top center of the frame. Clouds that appear white consist mainly of water ice. Clouds that appear orange or brown contain dust.
(MSSS / NASA)
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Swiss cheese

Global Surveyor captured images of a frost pattern at Mars' south polar ice cap that looks like Swiss cheese. The south polar cap is the only region on the Red Planet to contain such formations.
(NASA / JPL / Malin Space Science)
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Purple Planet

A false-color image from the Opportunity rover, released Feb. 9, 2004, accentuates the differences between a green-looking slab of Martian bedrock and orange-looking spheres of rock. Scientists likened the "spherules" to blueberries embedded within and scattered around muffins of bedrock. The spherules are thought to have been created by the percolation of mineral-laden water through the bedrock layers.
(NASA / JPL / Cornell University)
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Dunes of Mars

A false-color view from NASA's Opportunity rover, released Aug. 6, 2004, shows the dune field at the bottom of Endurance Crater. The bluish tint indicates the presence of hematite-containing spherules ("blueberries") that accumulate on the flat surfaces of the crater floor.
(NASA / JPL / Cornell University)
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Alien junkyard

The Opportunity rover looks at its own heat shield, which was jettisoned during the spacecraft's descent back in January 2004, on Dec. 22, 2004. The main structure from the heat shield is at left, with additional debris and the scar left by the shield's impact to the right. The shadow of the rover's observation mast is visible in the foreground.
(NASA / JPL)
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Devil on Mars

This image shows a mini-whirlwind, also known as a dust devil, scooting across the plains inside Gusev Crater on Mars, as seen from the Spirit rover's hillside vantage point on April 18, 2005.
(NASA / JPL)
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Rub al Khali

The tracks of NASA's Opportunity rover are visible in a panoramic picture of a desolate, sandy stretch of Martian terrain in Meridiani Planum, photographed in May 2005 and released by NASA on July 28. "Rub al Khali" (Arabic for "Empty Quarter") was chosen as the title of this panorama because that is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.
(NASA / JPL / Cornell University)
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Double moons

Taking advantage of extra solar energy collected during the day, NASA's Spirit rover spent a night stargazing, photographing the two moons of Mars as they crossed the night sky. The large bright moon is Phobos; the smaller one to its left is Deimos.
(NASA / JPL / Cornell / Texas A&M)
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Mars in the round

A 360-degree panorama shows a stretched-out view of NASA's Spirit rover and its surroundings on the summit of Husband Hill, within Mars' Gusev Crater. The imagery for the panorama was acquired in August, and the picture was released on Dec. 5.
(NASA)
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Fossil delta

Scientifically, perhaps the most important result from use of the Mars Orbiter Camera on NASA's Mars Global Surveyor has been the discovery in November 2003 of a fossil delta located in a crater northeast of Holden Crater.
(NASA / JPL / MSSS)
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Underneath the ice

This view taken in January 2005 shows sharp detail of a scarp at the head of Chasma Boreale, a large trough cut by erosion into the Martian north polar cap and the layered material beneath the ice cap.
(NASA / JPL / MSSS)
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Celestial celebration

Controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., cheer on Friday after hearing that Mars Reconnaissance Orbiter successfully made it into orbit around the Red Planet.
(Phil McCarten / Reuters)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.

The Phoenix Mars Lander set to land Sunday may represent a clean slate for NASA's past failed or canceled Martian missions, but its technological lineage also resembles Frankenstein's monster.

The spacecraft will land on the Red Planet with baggage that includes a backhoe-like robotic arm, a miniature chemistry set, and a laser-guided weather station.

"Most of the instruments have heritage from other missions," said Michael Gross, Phoenix payload manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Those heritage technologies developed for previous Mars missions such as Mars Surveyor Lander and Mars Polar Lander came in useful to outfit the $420 million Phoenix mission, which seeks to uncover the history of water on Mars by digging beneath the arctic surface. The spacecraft is set to land on May 25 on a six-month mission to determine whether the region may have once been habitable for primitive life.

Digging the Red Planet
However, Gross and other engineers had to remind themselves that Phoenix's new science mission came with new demands.

"We were counting on the heritage of the 2001 (Mars Surveyor Lander) arm, and we had to redesign the whole thing," Gross told SPACE.com. "There's a comfort level, but also pitfalls with heritage that you want to make sure you don't walk into."

The original robotic arm lacked the physical power to dig into the frozen Martian tundra, so engineers strengthened the joints and switched the arm material from aluminum to steel. They also replaced the original scoop with the Icy Soil Acquisition Device, which has several tricks to deal with the ice-hardened layer beneath the looser regolith soil on the surface.

First the nearly eight-foot robotic arm uses a backhoe motion to clear away loose regolith and expose the icy layer. A blade on the front of the scoop can try a bit of scraping, but the real digging for ice samples requires a small drill in the back of the scoop.

The spring-loaded drill is sprung against the ground and turned on, rotating and grinding against the icy soil using the spring's pressure. Wrist movements push the loosened ice samples into a chamber for further testing.

"Within about a minute or so, it kicks a fair amount of material into the scoop or chamber," said Peter Smith, Phoenix principal investigator at the University of Arizona, Tucson. Smith added that the drill would do its excavation two or three times.

The robotic arm also has scraper blades on the bottom that can clear away material and continue tearing up the icy regolith, Gross said. The arm can dig down as far as 20 inches, the deepest that anyone has gone on Mars.

Tasting Mars
Once Phoenix secures samples, it breaks out the first-ever wet chemistry lab on Mars. The Microscopy, Electrochemistry, and Conductivity Analyzer allows scientists to analyze loose regolith soil for levels of acidity, minerals, and conductivity, using single-use beakers the size of teacups where Martian soil dissolved in water can be soaked, stirred and measured.

MECA will also use atomic-force microscopes that can examine the Martian soil down to 10 nanometers, or 10,000 times thinner than a sheet of paper — the smallest scale ever examined on Mars. Signs of clay or other material in the loose regolith could indicate the past presence of water.

Another MECA instrument can detect any lingering wetness in the regolith soil, and examine how heat changes within the soil. The thermal and electrical conductivity probe resembles a spiked "knuckle" that the robotic arm can dig into the excavated area.

"The upper surface stuff done by MECA can look through the dry environment for remnants of water," Gross said. "TEGA [Thermal and Evolved Gas Analyzer] will actually look for the water."

The robotic arm will feed soil and ice into eight TEGA ovens, each the size of a ballpoint pen ink cartridge. The one-use ovens can then slowly heat the samples up to 1,800 degrees F, which allows scientists to measure and analyze any changes from solid to liquid to gas. The TEGA tool also contains a new spectrometer that can sniff heated gases for their chemical signature.

With six months to study Mars and only a limited number of ovens and beakers, Phoenix researchers plan to take extra care in choosing exactly which bits of Martian soil and ice to test.

"It's called negotiation," Smith has said. "We'll get in a room and we'll negotiate. If it comes up to me, I'll make the decision."

Most of the Phoenix mission's new technology rests in the Meteorological Station, which can bounce powerful laser pulses off dust and ice particles in the Martian atmosphere. The reflected pulses will provide information about the atmospheric particles.

The combination of old technology and newer instruments required a lot of "system engineering making sure everything would play together," Gross noted. But the proud international heritage of instruments from the United States, Canada and Germany will hopefully help Phoenix hit Martian pay dirt after its nail-biting descent.